Semiconductor device evaluation apparatus and semiconductor device evaluation program product

ABSTRACT

A semiconductor device evaluation apparatus for correctly measuring emission noise of a semiconductor device includes: an electromagnetic field measurement unit for measuring a two-dimensional electromagnetic field distribution in a plane parallel to an upper surface of a semiconductor device; a distribution image generation unit for not only extracting a distribution of an electromagnetic field higher than a threshold value determined in advance from the electromagnetic field distribution of the semiconductor device measured by the electromagnetic field measurement unit but converting the extracted electromagnetic field distribution to a distribution image in a two-dimensional plane; an image collation unit for collating the distribution image generated by the distribution image generation unit with a projected image, generated in advance, of an interconnect and a lead frame of the semiconductor device; and an emission source specifying unit for specifying an interconnect or a lead frame whose images are superposed, if the images of the electromagnetic field distribution, and the interconnects and lead frames are superposed on each other in collation by the image collation unit, as an emission source.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a semiconductor deviceevaluation apparatus and particularly, to a semiconductor deviceevaluation apparatus for evaluating an electromagnetic near-fieldstrength of a semiconductor device. The present invention furtherrelates to a magnetic field sensor suitable for use in the semiconductordevice evaluation apparatus.

[0003] 2. Description of the Prior Art

[0004] EMI (electromagnetic interference) evaluation of electronicequipment is to measure an emitted far-field of the electronic equipmentaccording to measurement methods stimulated in various kinds ofstandards and evaluate whether or not an emission quantity meets astandard. If the standard is not met, further detailed evaluation isperformed at levels of a case and a print circuit board of theelectronic equipment as evaluation objects in order to specify aproblematic part in the equipment.

[0005] As a fundamental evaluation method, there can be named a methodin which electrical parameters such as a current, a voltage and anelectromagnetic near-field and the like at parts of an object forevaluation are measured by proper means and a part which has apossibility to cause a problem in terms of electromagnetic compatibilityis thus specified. For example, in Japanese Patent Application Laid-OpenNo. 4-230874, there is disclosed a method in which a two-dimensionalelectromagnetic strength measurement apparatus is employed, a printcircuit board built in electronic equipment is extracted therefrom, amagnetic field sensor is disposed in the vicinity of the print circuitboard, a two-dimensional magnetic field distribution is measured in aplane which is parallel to the board and it is eventually evaluated thata part where a high magnetic strength is measured has a high possibilityof being a noise source.

[0006] In such a conventional example, in many cases, there has beenadopted a method In which, at first, a problematic part and a mechanismof a problematic circuit function are selected by narrowing candidatesfrom a list thereof according to experiences and expertise of a personin measurement and an optimal EMC countermeasure is attained. For acountermeasure in an EMC, it is important to conduct non-contactmeasurement in order to suppress, to the lowest level possible, anelectrical influence on a circuit function of the electronic equipmentwhich is an evaluation object. When a semiconductor device itself (forexample, a semiconductor package) as an object for evaluation is, in anon-contact manner, measured to specify an internal problematic part asin the case of electronic equipment, there arises a necessity for anelectromagnetic sensor with a spatially high resolving power.

[0007] However, a practical electromagnetic sensor adaptable for asemiconductor device has not been known.

[0008] As a noise evaluation method of a semiconductor device, there isavailable a document: “Electromagnetic Emission (EME) Measurement ofIntegrated Circuits, DC to 1 GHz” IEC 47A/429/NP NEW WORK ITEM PROPOSAL,1996.2, published by IEC in which a measurement method for emissionnoise from a semiconductor device is shown. Besides, there is alsoavailable a document: “Electromagnetic Compatibility MeasurementProcedures for Integrated Circuits” IEC 47A/428/NP NEW WORK ITEMPROPOSAL, 1996.2, published by IEC in which a measurement method forconduction noise which occurs in each pin of a semiconductor device isshown.

[0009] Two measurement methods for an emission noise from asemiconductor device package are shown. One will be shown below. Asemiconductor device which is an object for evaluation is mounted on asurface of a print circuit board and peripheral circuitry for operatingthe semiconductor device is constructed on the rear surface thereof. Theprint circuit board is fixed on a plane in the top portion of a TEM cellso that a surface of the print circuit board on which a semiconductordevice is mounted resides in the inside of the TEM cell. One end of theTEM cell is constructed as a reflection-free terminal and the other endconnected to a spectrum analyzer, and thereby emission noise from thesemiconductor device only can be measured excluding influences from theperipheral circuitry.

[0010] A second method will be shown below. A semiconductor device as anobject for evaluation is mounted on a surface of a print circuit boardand peripheral circuitry for operating the semiconductor device isconstructed on the rear surface thereof. The print circuit board isdisposed with the surface on which the semiconductor device is mountedfacing upward and a shielded loop constructed from a semi-rigid coaxialcable is arranged above the print circuit board. The vicinity of thesemiconductor device is scanned with the shielded loop along a planeparallel to the print circuit board by a scan mechanism and therebyemission noise from the semiconductor device only can be measured. Inthis case, the maximal value of outputs at measurement sites isevaluated as a problematic site to specify.

[0011] Then, a measurement method for conduction noise which occurs ineach pin of a semiconductor device package will be shown below. Astructure comprises a test board for mounting a semiconductor devicewhich is an object for evaluation and a main board for connecting thetest board and a spectrum analyzer thereby. The semiconductor device ismounted in the center of the circular test board and the test board isattached to the main board in the center thereof. Interconnects areprovided on each of the two boards radially toward the outside of theboard and conduction noise from the pins of the semiconductor device ismeasured by the spectrum analyzer which is connected to the pins throughconnectors of a coaxial type mounted in the vicinity of the outerperiphery of the main board.

[0012] As other examples, the following methods are named. For example,in Japanese Patent Application Laid-Open No. 64-65466, there isdisclosed an identification method for an electromagnetic field noisegenerating part in which a reference plane is imagined which intersectselectronic equipment, an arbitrary plane which is in parallel with thereference is scanned with an antenna, strengths of electromagnetic fieldnoise and noise generating sites are sampled, and thereby a generationdistribution map for electromagnetic noise of the electronic equipmentas viewed from the arbitrary plane set in advance is expressed in theform of a contour map. Besides, in Japanese Patent Application Laid-OpenNo. 5-119089, there is disclosed an electromagnetic radiationvisualization apparatus, in which a variable-length dipole antenna 3 ofa measurement unit 1 is fixed in length which matches a measurementfrequency and the antenna 3 is moved by a three-dimensional movementmechanism 4 in an anechoic electromagnetically chamber 7 while scanning.At this point, the interior of the electromagnetically anechoic chamber7 is optically made dark and a brightness of a lamp 2 which isproportional to an electric field strength at each measurement site isrecorded by a sterocamera 5 with exposure. Furthermore, in JapanesePatent Application Laid-Open No. 6-58970, there is disclosed aninvention having an object to provide an EMI measurement apparatus whichcan three-dimensionally measure noise along X-Y-Z directions on thefront side of a print wiring board on which electronic parts with muchof unnecessary radiation are mounted, and which can two-dimensionallymeasure noise along X-Y directions on the rear side thereof. This is anEMI measurement apparatus which has a construction in which a printwiring board is set to an antenna for measuring an interference in whichwinding coils are arranged in an array and a magnetic near-field probeis mounted on the fore end arm of a robot which can be driven alongX-Y-Z directions on the front side of the print wiring board in order tomeasure a noise generating source of the print wiring board on which anelectronic part which is rich in unnecessary radiation is mounted,whereby a distribution of magnetic field strengths in unnecessaryradiation on both sides, front and rear, is measured. In addition, inJapanese Patent Application Laid-Open No. 9-80098, there is disclosed anEMC probe, by which a spatial resolving power is increased and ameasurement band region is sufficiently secured. This comprises aflexible board whose surface is insulated and a winding 11 with a singleturn or a plurality of turns for detecting a magnetic near-field vectorof an object for measurement, while being disposed obliquely, thewinding being constructed from a metal thin film formed in a plane onthe board.

BRIEF SUMMARY OF THE INVENTION Object of the Invention

[0013] Problematic points of a measurement method for emission noisefrom a semiconductor device package will be described below. First ofall, problematic points of a method using a TEM cell will be described.

[0014] A first problematic point is that there is available no detailedstandards for designing of a print circuit board on which asemiconductor device is mounted and thus an evaluation result depends ona design of the print circuit board. Besides, since a print circuitboard on which a semiconductor device is mounted is square, there can befour ways to mount the semiconductor device, but a result is differentaccording to a way to be mounted.

[0015] The reason why is considered that an electromagnetic wave emittedfrom a surface of a print circuit board on which a semiconductor deviceis mounted has a polarized wave and a pin position whose emission islarge in quantity is changed, whereby emission characteristics arelargely changed.

[0016] A second problematic point is that if a quantity of emissionnoise exceeds a tolerable level, though the emission noise can correctlybe measured, a countermeasure is required. However, this method is veryhard to specifically locate a problematic site.

[0017] The reason why is that since the semiconductor device is presentin the TEM cell, it is impossible to correctly confirm what part of thesemiconductor device has a problem.

[0018] A third problematic point is that a print circuit board isrequired to be prepared for each semiconductor device for evaluation,which entails cost in terms of time and economy.

[0019] A fourth problematic point is that since the semiconductordevices are evaluated under constant conditions, evaluation results havechances in which the results are not effective for use conditions by auser.

[0020] In addition, problematic points of a method using a shielded loopwill be described.

[0021] A first problematic point is that there Is available no detailedstandards for designing of a print circuit board on which asemiconductor device is mounted and thus an evaluation result depends ona design of the print circuit board.

[0022] The reason why is considered that an electromagnetic wave emittedfrom a surface of a print circuit board on which a semiconductor deviceis mounted has a polarized wave and thereby emission characteristics arelargely changed.

[0023] A second problematic point is that if a quantity of emissionnoise exceeds a tolerable level, though the emission noise can correctlybe measured, a countermeasure is required. However, this method is veryhard to specifically locate a problematic site.

[0024] The reason why is that a small-sized type is hard to be realizedsince the shielded loop is prepared by a semi-rigid coaxial cable and asa result, a structure has an insufficient spatial resolving power and itis impossible to correctly confirm what part of a semiconductor devicehas a large emission.

[0025] A third problematic point is that a print circuit board isrequired to be prepared for each semiconductor device for evaluation,which entails cost in terms of time and economy.

[0026] A fourth problematic point is that since the semiconductordevices are evaluated under constant conditions, evaluation results havechances in which the results are not effective for use conditions by auser.

[0027] Furthermore, problematic points of a measurement method forconduction noise which occurs in each pin of a semiconductor packagewill be described below.

[0028] A first problematic point is that since electrical connectionbetween the test board and the main board depends on point contactformed by pressure bonding of metal pin, transmission characteristicscome to be in disorder under a high frequency band close to 1 GHz.

[0029] The reason why is considered that an impedance becomesdiscontinuous in the point contact portion.

[0030] A second problematic point is that a test board has to be newlyprepared for each semiconductor device for evaluation, which entailscost in terms of time and economy.

[0031] A third problematic point is that since the semiconductor devicesare evaluated under constant conditions, evaluation results have chancesin which the results are not effective for use conditions by a user.

[0032] A fourth problematic point is that evaluation of a semiconductordevice which requires circuitry with a large construction is hard to beperformed because of requirement for a large space.

[0033] In this way, conventional examples have had inconveniences that,firstly, it is hard to correctly measure emission noise of asemiconductor device and secondly, even if emission noise can bemeasured, it is impossible to specify what part in the semiconductordevice is problematic.

SUMMARY OF THE INVENTION

[0034] It Is an object of the present invention to provide a magneticfield sensor by which the above described inconveniences whichconventional examples have had are improved and especially, emissionnoise of a semiconductor device can correctly be measured. It is anotherobject of the present invention to provide a semiconductor deviceevaluation apparatus with good workability and high reliability whichcan perform EMI evaluation of a semiconductor device.

[0035] The present invention, therefore, has a configuration whichcomprises: an electromagnetic field measurement unit for measuring anelectromagnetic field distribution emitted from a semiconductor device;an electromagnetic field distribution extracting unit for extracting adistribution of an electromagnetic field higher than a threshold valuedetermined in advance and positional information of the distributionfrom an electromagnetic field distribution of a semiconductor devicewhich is measured by the electromagnetic field measurement unit; and apart specifying unit for specifying a part of an object for measurementan electromagnetic field emitted from which is high among parts of theobject for measurement based on the positional information of theelectromagnetic field distribution which is extracted by theelectromagnetic field distribution extracting unit. This allows theobjects described above to be attained.

[0036] The electromagnetic field measurement unit measures anelectromagnetic field distribution which is emitted from a semiconductordevice. Then, the electromagnetic field distribution extracting unitextracts a distribution of an electromagnetic field higher than athreshold value determined in advance and positional information of thedistribution from an electromagnetic field of the semiconductor device.The positional information may be, for example, a distribution image inwhich information on whether or not an electromagnetic field exceeds thethreshold is stored in a pixel corresponding to the information. Thepart specifying unit specifies a part an electromagnetic field of whoseemission is high based on the positional information of theelectromagnetic field distribution. For example, a part of asemiconductor device such as an interconnect or a lead frame isspecified. Thus, evaluation of an electromagnetic field emitted from thesemiconductor device is effected.

BRIEF DESCRIPTION OF THE DRAWINGS

[0037]FIG. 1 is a block diagram showing a schematic configuration of asemiconductor device evaluation apparatus according to the presentinvention;

[0038]FIG. 2 is a flowchart showing an example of processing by thesemiconductor device evaluation apparatus shown in FIG. 1;

[0039] FIGS. 3(A) to (D) are representations for illustrating examplesof images used In steps shown in FIG. 2, and FIG. 3(A) is arepresentation showing an example of a picked-up image, FIG. 3(B) is arepresentation showing an example of a distribution image, FIG. 3(C) isa representation showing an example of a collation image, and FIG. 3(D)is a representation showing an example of a extracted image;

[0040]FIG. 4 is a block diagram showing a configuration of an embodimentof the present invention;

[0041]FIG. 5 is a block diagram showing a configuration of anelectromagnetic field sensor and a measurement unit shown in FIG. 4;

[0042]FIG. 6 is a perspective view showing a detailed configuration ofthe multilayer magnetic field sensor shown in FIG. 5;

[0043]FIG. 7 is a perspective view showing a construction to improve asensitivity of the multilayer magnetic field sensor shown in FIG. 5;

[0044]FIG. 8(A) is a diagram showing a layer configuration of amultilayer magnetic field sensor having a reinforcement base member onone side, and FIG. 8(B) is a diagram showing a layer configuration of amultilayer magnetic field sensor having reinforcement base membersrespectively on both sides;

[0045]FIG. 9 is a perspective view showing a construction of amultilayer magnetic field sensor having a fourth layer;

[0046] FIGS. 10(a), (b) are front views showing configuration ofmultilayer magnetic field sensors, and FIG. 10(a) is a front view of amultilayer magnetic field sensor having a base member at the lowest partand FIG. 10(b) is a front view of a multilayer magnetic field sensorhaving a plurality of base members at the lowest part;

[0047]FIG. 11 is a front view of a multilayer magnetic field sensorhaving a base member outside a C shaped pattern;

[0048] FIGS. 12(a) to (f) are diagrams showing steps of a fabricationprocess for a multilayer magnetic field sensor;

[0049] FIGS. 13(A), (B) are representations showing measurement resultsof two-dimensional magnetic field distribution, and FIG. 13(A) is arepresentation showing a measurement result in the embodiment and FIG.13(B) is a representation showing a measurement results in aconventional example;

[0050] FIGS. 14(A), (B) are graphs showing voltage vs. magnetic fieldconversion characteristics of a multilayer magnetic field sensor, andFIG. 14(A) is a graph showing values of a calibration coefficient for anamplitude and FIG. 14(B) is a graph showing values of a calibrationcoefficient for a phase;

[0051]FIG. 15 is a plan view showing pin assignment of a semiconductordevice package for evaluation; and

[0052]FIG. 16 is a plan view showing a structure of a conventionalshielded loop.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0053] Then, an embodiment of the present invention will be detailedwith reference to the accompanying drawings. FIG. 1 shows aconfiguration of the present invention. A semiconductor deviceevaluation apparatus comprises: an electromagnetic field measurementunit 1 for measuring a two-dimensional electromagnetic fielddistribution in a plane parallel to an upper surface of a semiconductordevice; a distribution image generation unit 2 for not only extracting adistribution of an electromagnetic field higher than a threshold valuedetermined in advance from the electromagnetic field distribution of thesemiconductor device measured by the electromagnetic field measurementunit 1 but converting the extracted electromagnetic field distributionto a distribution image in a two-dimensional plane; an image collationunit 3 for collating the distribution image generated by thedistribution image generation unit 2 with a projected image, generatedin advance, of an interconnect and a lead frame of the semiconductordevice; and an emission source specifying unit 4 for specifying aninterconnect or a lead frame whose images are superposed, as an emissionsource if the images of the electromagnetic field distribution, and theinterconnects and lead frames are superposed on each other in collationby the image collation unit 3.

[0054] The electromagnetic field measurement unit 1, for example,comprises: an electromagnetic field sensor 206 for measuring a magneticfield in the vicinity of a semiconductor device; a measurement unit 210for measuring an emitted electromagnetic field of the semiconductordevice using the electromagnetic field sensor 206; and a scan unit 207for scanning with the magnetic field sensor 206 in the vicinity of thesemiconductor device. The magnetic field sensor, in a preferableembodiment, comprises: a signal layer having a signal line; and a groundlayer which is a ground for the signal layer. In addition, theelectromagnetic field measurement unit 1 may further comprise anattenuator 47 connected to the electromagnetic field sensor 206 foreliminating an influence of either electric or magnetic field inmeasuring one of them.

[0055]FIG. 2 is a flowchart showing an example of processing by theconfiguration shown in FIG. 1. In the figure, numerals respectivelyindicate constituents performing portions of the overall processing. Asshown in FIG. 2, as a pretreatment, a lead frame of a semiconductordevice for evaluation are picked-up as an image (205). An example of apicked-up image 31 is shown in FIG. 3(A). In the picked up image 31, asemiconductor device chip 32 and a lead frame 33 are shown. In addition,pin assignment information of the semiconductor device is added to theimage 31 as an input (213).

[0056] Then, a two-dimensional electromagnetic field distribution in thevicinity of the semiconductor device for evaluation is measured (210). Athreshold value for an amplitude of an electromagnetic field isspecified automatically or by manual setting (211). Besides, adistribution of electromagnetic field which exceeds the threshold valueis extracted (214(a)). An example o an image of the electromagneticfield distribution 34 is shown in FIG. 3(B). Then, the distributionimage 34 is superposed on the picked-up image 31 as shown in FIG. 3(C)(214(b)). Furthermore, a lead frame whose images are superposed on eachother is extracted (214(c)). An example of an extracted image is shownin FIG. 3(D) Subsequently, a pin number of a lead frame which has beenextracted is identified (214(d)) and the pin number is transmitted as anoutput. Not only pin numbers but strengths of electromagnetic field ofall the pins may be transmitted as outputs in some of embodiments.

[0057] In the embodiment in which strengths of an electromagnetic fieldof all the pins are transmitted as outputs, the distribution imagegeneration unit 2 is provided with a function of segmenting anelectromagnetic field emitted from the semiconductor device between themaximum and minimum strength level into a plurality of emission strengthlevel intervals. In this case, the emission source specifying unit 4 ispreferably provided with a function of specifying an interconnect or alead frame which corresponds to each of the emission strength levelintervals. Besides, when emission strengths of lead frames aredetermined, the emission source specifying unit 4 is preferably providedwith a function of not only rearranging lead frames in the order ofemission strength level interval, but also transmitting the rearrangedlead frame information in the new order of the lead frames as an outputto the outside. In order that emission strengths of all lead frames aredetermined, a strength level interval is narrowed no change appears inthe newer order of the lead frames after rearrangement.

[0058] In an embodiment, the emission source specifying unit 4 isprovided with a function which transmits, as an output to the outside,synthesized information of lead frames rearranged according to theemission strength level intervals and pin assignment made by referencingto the pin assignment database showing functions of the lead frames in acircuit. Thus, evaluation data for the semiconductor device aregenerated. Semiconductor device evaluation data provided to a useraccording to the embodiment comprises, in a preferred embodiment: pinassignment data each of which shows a function in a circuit of acorresponding lead frame of the semiconductor device; electromagneticfield strength data each of which shows an electromagnetic fieldstrength which has been sensed by the electromagnetic field sensor oneach pin; and sets of order data each set of which defines a level inthe order of electromagnetic field strength for a pin corresponding tothe electromagnetic field strength data. Herein, pin assignment data andelectromagnetic field strength data are related with each other by alevel in the order according to order data. According to data with sucha structure, pin assignment data showing pin functions andelectromagnetic field strengths are indicated in the decreasing order ofelectromagnetic field strength. With this data structure, a lead framewhich is an emission source can be specified with ease, when an emittedelectromagnetic field of the semiconductor device exceeds an allowablelevel, information which is useful for a user to take measure to copewith the case, can be supplied to the user since even a function incircuit of a lead frame in question can be displayed.

[0059] Various functions of the distribution image generation unit 2,the image collation unit 3 and the emission source specifying unit 4 canbe realized by a processing apparatus such as a computer or the like. Inthis case, the processing apparatus comprises: a central processing unitsuch as CPU; a main storage unit, an input/output unit; an auxiliarystorage unit; and a display. Programs which are used for the computer toexecute the functions described above are stored in the auxiliarystorage unit. Storage of the programs to the auxiliary storage unit maybe effected through a communication line in addition to a method inwhich the programs are introduced from a storage medium such as a CD-ROMor the like by way of the input/output control unit.

[0060] The programs comprises as commands to run on the processingapparatus: a command extracting an electromagnetic field distributionhigher than a threshold value determined in advance from anelectromagnetic field distribution in the vicinity of a semiconductordevice measured by the electromagnetic field sensor 206; a command ofconverting the electromagnetic field distribution to a distributionimage in a two-dimensional plane; a command of collating thedistribution image with a projected image of interconnects and leadframes of the semiconductor device which have been generated; a commandof specifying an interconnect or a lead frame which is superposed oneach other as an emission source, if the images of the electromagneticfield distribution, and the interconnects and lead frames are superposedon one another by the collation. These commands each of which forces afunction to be executed include another program which is used to havethe computer realize a desired function in dependence on the operatingsystem and other application programs of the processing apparatus. It isneedless to say that the processing apparatus may entirely be controlledby the program only.

[0061] Various functions of the distribution image generation unit andthe emission source specifying unit can be realized by logic circuits.The data for evaluation of a semiconductor device described above mayalso be constructed from a logic circuit.

EXAMPLES Semiconductor Device Evaluation Apparatus

[0062]FIG. 4 is a block diagram showing a configuration of an embodimentof the present invention. In an example shown in FIG. 4, thesemiconductor device evaluation apparatus comprises: a mounting section202 for mounting a semiconductor device 201 for evaluation; asemiconductor device drive unit 203, 204 for driving the semiconductordevice 201 mounted on the mounting section 202; an electromagnetic fieldsensor 206 for sensing an electromagnetic field emitted from thesemiconductor device 201 which is driven by the semiconductor devicedrive unit 203, 204; a measurement unit 210 for measuring an output ofthe electromagnetic field sensor 206; an image pick-up unit 205 fortaking a photograph of patterns of interconnects or lead frames of thesemiconductor device 201; a scan unit 207 for conducting scanning withthe electromagnetic field sensor 206 and the image pick-up unit 205 inthree coordinate axis directions; an input unit 211 to which informationon a scan range, a scan pitch, a scan speed of the scan unit 207 and thelike, and information on settings of the image pick-up unit and themeasurement unit and the like are supplied as inputs; and a control unit208 for controlling the scan unit 207, the image pick-up unit 205 andthe measurement unit 210 according to information which is supplied asinputs to the input unit 211, wherein the control unit also receivesinformation from the measurement unit 210 and the image pick-up unit205. In the example shown in FIG. 4, an output from the image pick-upunit 205 is supplied to the control unit 208 as an input by way of theprocessing unit 209.

[0063] The semiconductor device evaluation apparatus further comprises arecord unit 212 which prepare and stores a two-dimensionalelectromagnetic field distribution based on information obtained fromthe measuring unit 210 and the image pick-up unit 205 by way of thecontrol unit 208; an arithmetic unit 214 which not only extracts anemitted electromagnetic field distribution higher than a threshold valuewhich can arbitrarily be set based on a two-dimensional electromagneticfield distribution which is prepared in the record unit 212, but alsospecifies an interconnect and a lead frame of the semiconductor devicewhich are large in emission quantity by projecting the extractedelectromagnetic field distribution on the image from the image pick-upunit 205; and an indication unit 215 for indicating the two-dimensionalelectromagnetic field distribution prepared by the record unit 212, theemitted electromagnetic field distribution with a high strength having alinear shape prepared by the arithmetic unit 214 and the image from theimage pick-up unit 205. Herein, the semiconductor device drive unit 203,204 has at least one of a semiconductor device drive circuit unit 203and a semiconductor device drive software activation unit 204.

[0064] The semiconductor device 201 which is an object for evaluation isfixed by the semiconductor device mounting section 202. Thesemiconductor device 201 is connected to at least one of thesemiconductor device drive circuit unit 203 and the semiconductor devicedrive software activation unit 204. The image pick-up unit 205 and theelectromagnetic field sensor 206 are fixed on the scan unit 207 andconnected to the control unit 208. An output of the image pick-up unit205 is connected to the control unit 208 by way of the processing unit209 and an output of the electromagnetic field sensor 206 is connectedto the control unit 208 by way of the measurement unit 210. The controlunit 208 to which the input unit 211 is connected is connected to therecord unit 212. The record unit 212 is connected to the indication unit215 by way of the arithmetic unit 214 to which the storage unit 213 isconnected.

[0065] When the semiconductor device 201 for evaluation is fixed on thesemiconductor device mounting section 202, the image pick-up unit 205which is fixed on the scan unit 207 which can perform scanning in thethree coordinate axis directions takes a photograph of lead frames andinterconnects of the semiconductor chip or the semiconductor devicepackage for evaluation in an evaluation region thereof. A photographicresult is stored as a picked-up image 31 shown in FIG. 3. The picked-upimage 31 is constructed from a lead frame image 33 and a semiconductorchip image 32. The picked-up image 31 is processed in the digital formaccording a necessity and thereafter, stored in the record unit 212 aselectronic information.

[0066] Then, the semiconductor device 201 for evaluation is set into anoperating state by the semiconductor device drive circuit unit 202 andthe semiconductor device drive software activation unit 203. A plane inparallel with a upper surface of the semiconductor device 201 forevaluation is scanned over an evaluation region with the electromagneticfield sensor 206 fixed on the scanning unit 207 which can performscanning in the three coordinate axis directions and an emittedelectromagnetic field from the semiconductor device 201 for evaluationis sensed and measured by the measurement unit 210 and the measuredtwo-dimensional electromagnetic field distribution image 34 is stored inthe record unit 212 as electronic information.

[0067] Then, a unit for specifying a lead frame will be described. Athreshold value g of amplitude is given to the arithmetic unit 214 as aninput from the input unit 211 and an electromagnetic field distribution34 with an amplitude larger than a threshold value is extracted in thearithmetic unit 214. Then, the picked-up image 31 and an image of thusextracted electromagnetic field distribution 34 are superposed on eachother while positioning both images using reference points respectivelyprovided in them. A resulted image is adopted as the collation image 35.Then, a lead frame which superposes the extracted electromagnetic fielddistribution 34 is further extracted to obtain the extracted image 36.

[0068] There are several methods to obtain the image 36. An example ofthe extraction methods will be shown below. The image 31 of a lead frameis segmented into n×n images. Therefore, x is segmented as x=x1 . . . xnand y is also segmented as y=y1 . . . yn. Only the image of the leadframe 33 left behind after the semiconductor chip image at the center iseliminated from the image 31 is expressed as a function A (x, y). Sincea semiconductor chip is normally rectangular for simplicity, theextraction can be executed comparatively with ease by using a generalimage processing method. Each lead frame is extracted from an image ofthe function A (x, y). Since a lead frame is an image having a linearshape, the extraction is performed using a method in which an imagehaving a linear shape is extracted. The results are classified intogroups, to form a set, each of which is composed of 9 images for eachlead frame, in which the set is named as LF.

[0069] LF={A1 (x, y, s1, l1, R1), A2 (x, y, s2, l2, R2), A3 (x, y, s3,l3, R3 ) . . . Ap (x, y, sp, lp, Rp)}

[0070] The x and y are coordinates and the sp is a numerical value whichis assigned to an image. At this point, in this set, the sp given is 1.A number of a lead frame which is obtained with reference to the pinassignment information of a semiconductor device is given to lk. Rk is aparameter which shows a level in the order of strength level intervalwhich is ordered by strength of emission from a lead frame as describedlater.

[0071] A set of pixels which are not included in LF is named as A0 (x,y, s0, l0) among A (x, y). Herein, there is given s0=0. Since there isno lead frame, there is given 1o=0. With the settings, the followingequation (1) is obtained. Then, an image 34 is expressed by B (x, y) andpixels in a region which exceeds a threshold value are given 1 andpixels which are lower than the threshold are given 0.

[0072] The following relations are set: B (x, g):=1 in the coordinateswhere an amplitude of an electromagnetic field is equal to or largerthan a threshold value and B (x, y):=0 in the coordinates where anamplitude of an electromagnetic field is less than a threshold value.

[0073] Herein, an arithmetic operation according to the equation (2) isperformed for each set B (x, y). $\begin{matrix}\text{[Equation~~1]} & \quad \\{{A\left( {x,y,s,l} \right)} = {\sum\limits_{k = 0}^{x}{{Ak}\left( {x,y,{sk},{lk}} \right)}}} & (1) \\{{qk} = {\sum\limits_{x = 1}^{x}{\sum\limits_{y = 1}^{x}\left\{ {{{Ak}\left( {x,y,{sk},{lk}} \right)} \cdot {B\left( {x,y} \right)}} \right\}}}} & (2)\end{matrix}$

[0074] Herein, the symbol “·” in the equation (2) is a symbol by whichan arithmetic operation according to the rule of binary operation suchas 0·0=0, 1·0=0, 1·1=1 is operated. Accordingly, only when a lead frameand an extracted distribution at which an electromagnetic field strengthis high are superposed on each other, a logical multiplication assumes1. That is, qk≧1. If there is no superposition at all, qk=0. All valuesof k with which qk≧1 are obtained. Values k which are sequentiallyobtained are added to a set named as Ck. The description made above ison processing performed in 214(a) to (d) of FIG. 2.

[0075] Then, in 215, the name of a pin is obtained based on a number 1kof a lead frame with reference to the pin assignment information 215 ofthe semiconductor device from the set Ck and the name and the number 1kare transmitted as outputs. In the above described way, a pin with ahigh electromagnetic field strength emitted therefrom can be specified.

[0076] Since a person who conducts measurement can set a threshold valueg to any value, each of lead frames can be specified while a value g ischanged from the maximum value of the measured electromagnetic fieldstrength to the minimum value thereof. For example, assume that themaximum and the minimum values of the measured electromagnetic fielddistribution F (x, y) are respectively Fmax and Fmin. Then, a strengthspace between the Fmax and Fmin is segmented into n intervals as in theequation (3).

h=(Fmax−Fmin)/n  Equation (3)

[0077] A threshold value is set at Fmax-h. Herein, if an operation inwhich a lead frame is specified is performed as described previously, alead frame which emits a strong emission can be specified. Rk of thelead frame which has been thus specified is stored with 1. The number 1is the number with which a level in the order of strength is judged.

[0078] Then, a g is set at Fmax−2h and a lead frame is specified.Herein, Rk of the lead frame which has been specified is stored with 2.At this point, the lead frame which was previously specified isexcluded. When threshold values g are sequentially changed as in such away from Fmax−2h, Fmax−3h . . . and to Fmax−Fmin while the operation isrepeated with the change of a threshold value going on, all lead framescan respectively be classified into corresponding strength levelintervals with setting of the threshold value g as an emissive powersection.

[0079] If the number n of segmentation is larger, a finer classificationcan be realized and the classification can be performed in such mannerthat all lead frames can respectively be specified into correspondingstrength level intervals. In this case, it has to be determined what themaximum number of segmentation is acceptable, but all that need to bedone for the determination is, repetition of segmentation operation andclassification of lead frames into strength level intervals till thenumbers of levels in the order of strength level intervals, that is thevalues of R1 . . . Rp are not changed any more in newer classificationeven if the number of segmentation is further increased at whichrepetition of the segmentation operation is terminated. If a number inthe order in Rk, lp and pin assignment information (a name of a pin) ofthe semiconductor device are transmitted together as outputs, the personwho conducts measurement can recognize lead frames in the decreasingorder of emission strength.

[0080] In an desirable example, there is preferably provided with afunction which calculates a current value in the semiconductor devicewhich is a cause of an emitted electromagnetic field based on a voltageshowing a magnetic field sensed by the electromagnetic field sensor 206and a magnetic permeability of a medium surrounding the semiconductordevice. That is, while, in the above example, a magnetic fielddistribution is measured, the magnetic field distribution can beconverted to a current distribution by simple calculation if a model canbe conceived which combines a magnetic field and a current. An output ofa magnetic field sensor is given by a voltage corresponding to a changein a magnetic field with respect to time in a plane including a loop andexpressed by the following equation (4). Herein, a dot placed on the topof a parameter means that the parameter is a complex number. At thispoint, a calibration coefficient to convert an output voltage to amagnetic field is defined by the following equation (5). A current whichflows along an endless straight conductor is given by the followingequation (6) from a magnetic field. According to the equation (6), acurrent can be obtained from an output voltage of a magnetic fieldsensor. $\begin{matrix}{V = {{- \mu}\quad {S\left\lbrack \frac{H}{t} \right\rbrack}}} & (4) \\{F = {H/V}} & (5) \\{I = {2\pi \quad {{rFV}\begin{bmatrix}{V:{voltage}} \\{H:{{magnetic}\quad {field}}} \\{l:{current}} \\{\pi:{{magnetic}\quad {permeability}\quad {of}\quad a\quad {surrounding}\quad {medium}}} \\{S:{{area}\quad {of}\quad a\quad {loop}}} \\{r:{{the}\quad {shortest}\quad {distance}\quad {from}\quad a\quad {straight}\quad {conductor}}} \\{\quad {{to}\quad a\quad {measurement}\quad {point}\quad {of}\quad a\quad {magnetic}\quad {field}}} \\{{A\quad {dot}\quad {on}\quad {the}\quad {top}\quad {of}\quad a\quad {parameter}\quad {expresses}\quad {that}}\quad} \\{{the}\quad {parameter}\quad {is}\quad a\quad {complex}\quad {{number}.}}\end{bmatrix}}}} & (6)\end{matrix}$

Electromagnetic Field Sensor

[0081] In FIG. 5, detailed constructions of the electromagnetic fieldsensor 206 and the measurement unit 249 are shown. In an example shownin FIG. 5, an LSI package 41 of a QFP type which is mounted on a printcircuit board is an object for evaluation. A power source which iselectromagnetically shielded is connected to the print circuit board 42and the whole of the print circuit board 42 is fixed on a jig 43 whichuses a metal plate with no plasticity using screws 44. A multilayermagnetic field sensor 46 shown in FIG. 6 is fixed on a scan jig 45 whichcan perform scanning in the three coordinate axis directions. An outputof the magnetic field sensor 46 is measured by a spectrum analyzer 49 byway of an attenuator 47 and an amplifier 48.

[0082] In FIG. 6, as a magnetic field sensor 46, a multilayer structureis adopted. The magnetic field sensor 46 has a structure in which thecoaxial cable 11 of a conventional shielded loop type magnetic fieldsensor shown in FIG. 16 is replaced with a triplate strip line. This cantheoretically be fabricated by a semiconductor device fabricationprocess and suitable for a smaller size. For this reason, a resolvingpower which is required for measurement on an emitted electromagneticfield of a semiconductor device can be sustained. In the example shownin FIG. 6, the sensor is constructed from a three layer base plate. Thefront-most layer is a first layer (ground layer) 501, and then a secondlayer (a signal layer) 502 and a third layer (a ground layer) 503 in theorder as viewed on the figure.

[0083] The first layer 501 and the third layer 503 are constructed froma C shaped conductor pattern 504 and a straight line conductor pattern505 which is connected to the C shaped conductor pattern 504 at themiddle point of continuous side of letter C(left side). An end of the Cshaped conductor pattern 504 is connected to a U shaped conductorpattern 507 of the second layer 502 through a via 506. The second layer502 is constructed from the U shaped conductor pattern 507 and astraight line conductor pattern 508 which is connected to an end of theU shaped pattern 507. The layers are respectively provided with signalline holes 510 and ground holes 511 for attaching a coaxial connector509.

[0084] The straight line conductor pattern 508 of the second layer 502is guided to a pad 512 on the first layer 501 through a via provided inthe signal line hole 510 and connected thereto by soldering. Thestraight line conductor patterns 505 on the first layer 501 and thethird layer 503 are connected to each other through a via provided inthe ground hole 511, and guided to the pad 513 provided on the firstlayer 501 and then connected thereto by soldering. The magnetic fieldsensor 46 has a square loop, being different from a circular shape ofthe conventional shielded loop, and therefore, can efficiently bepositioned close to interconnection. In this case, it is especiallyimportant that a shape of the fore end of the C shaped conductor patternis straight line.

[0085] Alternatively, as shown in FIG. 7, it is also possible to formthe C shaped conductor pattern of a fore end portion of a magnetic fieldsensor in such a manner that the portion has the same width as that of abase member. In this case, while a spatial resolving power is reduced ina longitudinal direction, the maximum sensitivity can be attained in alimited space of the base member. In the case where an object formeasurement is, for example, an interconnection conductor pattern on aprint circuit board, the magnetic field sensor is effective formeasurement of a high frequency magnetic field on an interconnection andan interconnection current if the magnetic field sensor is used in arange in which an influence of a wave length of a interconnection signalcan be neglected.

[0086] In the above described three layer structure, there is the case,by chance, where the structure cannot secure a sufficient strengthaccording a thickness of a base member (dielectric). In that case, byproviding a base member 514 besides the ground layer 513 as shown in alayer construction of FIG. 8(A), the strength of the structure isstrengthened. By providing a base member 516 of the same material asthat of the base member between the layers on the left side of the firstlayer as in FIG. 8(B), a symmetrical structure with respect to thesecond layer as the center can be realized. When a thickness of anadditional base member is close to those of the base members whichconstitute the layers while adopting this kind of structure, electricalcharacteristics of the magnetic field sensor can be stabilized and theadditional base member can also play a role as a reinforcement member.When additional base members 514, 516 each have a thickness sufficientlylarger than that of the base member between the layers, thecharacteristics of the magnetic field sensor can be stabilized, even ifthe thickness are made not to be equal to that between the layers.Below, there will be shown an example of the case where a base member514 is provided on one side of the three layer structure.

[0087] When a base member 514 is added, the connector 509 is mounted onthe base member 514 side for an electrical characteristic reason andthere is a chance where it is necessary for the fore end of a pin of theconnector 509 to be connected to the first layer. In the case, therearises a necessity to provide a fourth layer 515 in order to connect acircular outside conductor portion of the connector 509 to a rectangularconductor pattern as in FIG. 9. The fourth layer 515 has a rectangularconductor pattern of the same size as that of pads of the first layer501 and the third layer 503. Since the fourth layer 515 is used asconnection of the connector, the fourth layer 515 is kept in electricalconnection to the first and third layers using a via. Also, in the caseof FIG. 8(B) where base members are added on both sides, the fifth layer517 on the base member 516 maybe formed so as to have the same conductorpattern as that of the fourth layer 515.

[0088] Besides, as shown in FIGS. 10(a), 10 (b), when a base member 518or a base member 519 is added on the lower side to which a via islocated close, a distance d to an object for measurement can becontrolled. If the fore end of the magnetic field sensor is put intocontact to the object for measurement, measurement at a given distancecan be performed. FIG. 10(A) is an example in which a base member 518 isprovided across the whole length of the side. If t,he base member 519 isprovided in part of the side as in FIG. 10(b), means can be providedwhich can mechanically stabilize the fore end of the sensorcorresponding to a shape or deflection of an object for measurement whenin contact.

[0089] Since a shielded loop magnetic field sensor prepared with aconventional semi-rigid coaxial cable has a structure in which theinterior of the loop which works as a magnetic field sensor is filledwith air and an empty hole, the sensor is easy to be deformed andtherefore it is required know-how to fabricate the sensor. However,since a magnetic field sensor of the present invention has a stackedlayer structure, a structure that dielectric is provided inside a Cshaped conductor pattern which works as a magnetic field sensor isrealized. Hence, the structure is mechanically stable and has anadvantage that a special processing such as forming a hole is notrequired. Besides, as in FIG. 11, by using a board of a larger size thanthe outer size of the magnetic field sensor at the beginning of itsfabrication process, it becomes easier to provide the base member 520outside the C shaped conductor pattern, whereby a fabrication processcan be very flexible.

[0090] While a via for connection of the first, second and third layerstherebetween is formed at the fore end of the magnetic field sensor,there is a chance that a land 64 of the via 506 is large as shown inFIG. 12(b). The via 506 is formed with eccentricity from the center ofthe conductor pattern 507 of the second layer so that the via 506 shownin the figure is not extended toward the inside too much. In this case,since a distance from the sensor to the object for measurement is large,there arise problems, by chance, that a spatial resolving power isdecreased and therefore noise in the surrounding space is picked up withease. In such cases, by connecting with a via having a semicircular landor a via of the shape of a semicircle, as shown in FIG. 12(e), anincrease in distance from the sensor to the object can be decreased.

[0091] FIGS. 12(a) to 12(f) show a fabrication process for a multilayermagnetic field sensor having a semicircular land or via. First of all,as shown in FIGS. 12(a) to (c) in the left side, a first layer 61, asecond layer 62 and a third layer 63 are formed by etching. In thefigure, parts where connectors are mounted are omitted. When a via 506is formed, a land 64 is necessary. However, if the diameter of the land64 is larger than the width of a C shaped conductor pattern 504, theland 64 should be confined within the inner side of the ring-like Cshaped conductor pattern 504. In order to do this, the land 64 extendedover the periphery of the outer side of the C shaped conductor. Further,an extended part of the land 64 outside the ring-like C shaped conductorpattern is removed, along the lower side of the C shaped conductorpattern 504. Structures after the removal of the extended part of theland 64 are shown in FIGS. 5(d) to 5(f) each of which representing: thefirst layer 65, the second layer 66 and the third layer 67 where theland 68 of the second layer has a circle a part of which is cut off.

[0092] The magnetic field sensor 46 can be fabricated according to thefollowing process. In the first step, a second layer 502 having a signalline constituted of a U shaped conductor pattern of the second layer 507and a straight line conductor pattern 508 connected to an end of the Ushaped conductor pattern 507 is sandwiched between first and thirdlayers 501, 503, which work as grounds, each having a C shaped conductorpattern 504 and a straight line conductor pattern 508 connected to amiddle point of the continuous side(left side) of C shaped conductorpattern 504. In the second step, the first, the second and the thirdlayers are fixed in the order with additional insulating layers insertedtherebetween while sequentially superposing and at the same time, an endof the U shaped conductor pattern of the second layer is connected to anend of each of the C shaped conductor patterns of the first and thirdlayers by way of a via while passing through a gap between thenon-continuous side of C shaped conductor patterns.

[0093] In the course of superposition, not only is a land which isrequired in providing the via For the second layer having the U shapedconductor pattern wherein the land is confined within inside of aring-like C shaped conductor pattern when the diameter of the land islarger than the width of the C shaped conductor pattern, but alsopositioning is conducted so that the land is extended over the outsideof the ring-like C shaped conductor pattern. In addition, an extendedpart of the land outside the ring-like C shaped conductor pattern isremoved along the C shaped conductor pattern 504.

[0094] While a magnetic field sensor has to receive a magnetic fieldonly, there is a possibility to receive an electric field, though it isnot much. For that reason, an influence of the electric field can beeliminated by inserting an attenuator 47 connected to the magnetic fieldsensor. Of the entire output of the magnetic field sensor, an output ina normal mode thereof is originated from a magnetic field but an outputin a common mode thereof is generally originated from an electric field.While the output in the normal mode is guided to the measurement unitwithout any problem, the output in the common rode causes a resonancebetween the measurement unit and the magnetic field sensor due tomismatching. Besides, the output in the normal mode is very much largerin amplitude than that of the common mode. Accordingly, the common modewhich is considered to be caused by an influence of an electric fieldcan be eliminated by inserting an attenuator between the magnetic fieldsensor and the measurement unit.

[0095] As shown in FIG. 5, the magnetic field sensor 46 is disposed at aheight so as to contact the upper surface of the semiconductor devicepackage 41, and the print circuit board 42 which is mounted on thefixing jig 43 is fixed so that scanning axes in two-dimensional scanningof the magnetic field sensor 46 are respectively parallel to the sidesof the semiconductor device package 41 facing the magnetic field sensor46. An evaluation region is adjusted so as to include the entiresemiconductor device package 41 and the magnetic field sensor 46 islocated at an origin (0, 0) set as an initial state. Then, the printcircuit board 42 is made to enter the operating state. A frequency inmeasurement is set to 320 MHz which is already known as a frequency atwhich unnecessary emission is large, as a result of measurement in anemitted far-field measurement. The spectrum analyzer 49 is set so thatit can measure an amplitude at 320 MHz.

[0096] An x-y plane parallel to the upper surface of the semiconductordevice package 41 is scanned with the magnetic field sensor 46 by thescan jig 45 and an output of the magnetic field sensor 46 at each set ofcoordinates is measured by the spectrum analyzer 49 with the attenuator47 and the amplifier 48 interposed therebetween to attain atwo-dimensional magnetic field (Hx) distribution. Then, the magneticfield sensor 46 is rotated about the z coordinate axis along a verticaldirection as an axis of rotation by 90 degrees and thereafter antwo-dimensional magnetic field (Hy) distribution is attained in the sameway. Thus attained two magnetic field distributions are synthesized bythe following equation (7) to obtain one magnetic field distribution 71in FIG. 6. $\begin{matrix}\text{[Equation~~3]} & \quad \\{H = \sqrt{H_{x}^{2} + H_{y}^{2}}} & (7)\end{matrix}$

[0097] However, since values of an output voltage of the magnetic fieldsensor 46 are obtained in the spectrum analyzer 49, there is a need toknow a calibration coefficient to convert an output voltage to amagnetic field. Calibration coefficient characteristics of the magneticfield sensor 46 are shown in FIGS. 14(A), 14(B) and the figures showcalibration coefficients for a amplitude 81 and a phase 82. A strengthand a phase of a magnetic field are obtained by applying thecoefficients to an output voltage measured by the spectrum analyzer 49.Only magnetic field strength distributions are shown in FIGS. 13(A),13(B). Square frames 72 appeared in the distribution maps 71 of FIGS.13(A), 13(B) indicate the outline of the semiconductor device package41.

[0098] From the distribution 71 shown in FIG. 13(A), it is confirmedthat a magnetic field is stronger in stripe patterns along lead frameswhich are radially extended from the center of the semiconductor devicepackage. When the pin assignment 91 of the semiconductor device package41 for evaluation shown in FIG. 14 is referred to with respect of thepatterns, pins each of which has a high emitted magnetic field can bespecified. On the other hand, a two-dimensional magnetic fielddistribution 101 attained when a conventional magnetic field sensor of aloop radius 5 mm (FIG. 16) is used is shown in FIG. 13(B) and only asmaller number of large amplitudes are found in the distribution. Thisis considered because a resolving power is reduced for the reason thatsince a loop is large, magnetic fields of lead frames are synthesizedbefore measurement with the result that strengths of amplitudes close toeach other are averaged.

[0099] According to the embodiment, as described above, the followingeffects are realized.

[0100] A first effect is that evaluation can be performed on any ofsemiconductor devices on a wafer, in a package and in a mounted state onthe print circuit board. In the cases of semiconductor devices on awafer or in a package, EMI evaluation can be performed on the specimenmounted on a general purpose semiconductor tester or the like. In thecase where the semiconductor device is mounted on the print circuitboard, EMI evaluation can be performed as shown in the example.

[0101] The reason why is that since a non-contact electromagnetic fieldsensor is used, any interconnection can be evaluated with no evaluationpad used for a measurement probe.

[0102] A second effect is that the evaluation can be performed at a lowcost.

[0103] The reason why is that there is no need to prepare a mountingboard dedicated for each different kind of semiconductor device incertain state for evaluation.

[0104] A third effect is that an interconnect and a lead frame withlarge unnecessary emission can quickly be specified with ease.

[0105] The reason why is that an interconnect and a lead frame inquestion can be specified by first taking a photograph of each object,then measuring a two-dimensional electromagnetic field distribution inthe vicinity of the semiconductor device and further collating bothkinds of image information thus attained with each other to visuallyconfirm the result.

[0106] A fourth effect is that an interconnect and a lead frame withlarge unnecessary emission can be specified with precision.

[0107] The reason why is that by using a small-sized magnetic fieldsensor of a stacked layer structure, a two-dimensional magnetic fielddistribution with high resolution is attained and then in order tospecify an interconnect and a lead frame, the two-dimensional magneticfield distribution is related with positional information of aninterconnect and a lead frame of a semiconductor device, for example pinassignment.

[0108] Since the present invention is configured and functioned asdescribed above, an electromagnetic field distribution sensor measures adistribution of an electromagnetic field emitted from a semiconductordevice and a part specifying unit specifies a part with high emittedelectromagnetic field based on positional information of anelectromagnetic field distribution such as a distribution image. Forexample, since a part of a semiconductor device such as an interconnect,a lead frame or the like with large emitted electromagnetic fieldstrength are specified, therefore, evaluation of an electromagneticfield emitted from a semiconductor device can be performed on each partthereof and as a result, an excellent semiconductor device evaluationapparatus which has heretofore not been encountered can be provided.

[0109] The invention may be embodied in other specific forms withoutdeparting from the spirit or essential characteristic thereof. Thepresent embodiments are therefore to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than by the foregoingdescription and all changes which come within the meaning and range ofequivalency of the claims are therefore intended to be embraced therein.

[0110] The entire disclosure of Japanese Patent Application No.10-242916 (Aug. 28, 1998) including specification, claims, drawings andsummary are incorporated herein by reference in its entirety.

What is claimed is:
 1. A semiconductor device evaluation apparatuscomprising: an electromagnetic field measurement unit for measuring anelectromagnetic field distribution emitted from a semiconductor device;an electromagnetic field distribution extracting unit for extracting adistribution of an electromagnetic field higher than a threshold valuedetermined in advance and positional information of the distributionfrom an electromagnetic field distribution of a semiconductor devicewhich is measured by the electromagnetic field measurement unit; and apart specifying unit for specifying a part of the semiconductor devicewhich is high in emitted electromagnetic field among parts thereof basedon the positional information of the electromagnetic field distributionwhich is extracted by the electromagnetic field distribution extractingunit.
 2. A semiconductor device evaluation apparatus comprising: anelectromagnetic field measurement unit for measuring a two-dimensionalelectromagnetic field distribution in a plane parallel to an uppersurface of a semiconductor device; a distribution image generation unitfor not only extracting a distribution of an electromagnetic fieldhigher than a threshold value determined in advance from theelectromagnetic field distribution of the semiconductor device measuredby the electromagnetic field measurement unit but also converting theextracted electromagnetic field distribution to a distribution image inthe two-dimensional plane; an image collation unit for collating thedistribution image generated by the distribution image generation unitwith a projected image, generated in advance, of an interconnect and alead frame of the semiconductor device; and an emission sourcespecifying unit for specifying an interconnect or a lead frame whoseimages are superposed as an emission source if the images of theelectromagnetic field distribution, and the interconnects and leadframes are superposed on each other in collation by the image collationunit.
 3. The semiconductor device evaluation apparatus according toclaim 2, wherein the distribution image generation unit is provided witha function of segmenting an electromagnetic field emitted from thesemiconductor device between the maximum and minimum strength level intoa plurality of strength level intervals according to emission strengthand the emission source specifying unit is provided with a capability ofspecifying an interconnect or a lead frame which corresponds to each ofthe emission strength level intervals.
 4. The semiconductor deviceevaluation apparatus according to claim 3, wherein the emission sourcespecifying unit is provided with a function of not only rearranging leadframes in the order of emission strength level intervals, but alsotransmitting the rearranged lead frame information in the new order ofthe lead frames as an output to the outside.
 5. The semiconductor deviceevaluation apparatus according to claim 4, wherein the distributionimage generation unit is provided with a function of narrowing theemission strength level intervals till no change appears in the newerorder of the strength level intervals of leads after rearrangement ofthe strength level intervals of the lead frames by the emission sourcespecifying unit.
 6. The semiconductor device evaluation apparatusaccording to claim 5, wherein the emission source specifying unit isprovided with a capability which transmits synthesized information ofthe lead frames rearranged according to the emission strength levelintervals and pin assignment made by referencing to the pin assignmentdatabase showing functions of the lead frames in a circuit defined inadvance as an output to the outside.
 7. The semiconductor deviceevaluation apparatus according to claim 6, wherein the electromagneticfield measurement unit comprises: a signal layer having a signal line;and a magnetic field sensor having a ground layer which works as aground for the signal layer.
 8. The semiconductor device evaluationapparatus according to claim 7, wherein the emission source specifyingunit is provided with a function which calculates an electric currentvalue in the semiconductor device which is a cause of an emittedelectromagnetic field based on a voltage showing the magnetic fieldsensed by the magnetic field sensor and a magnetic permeability of amedium surrounding the semiconductor device.
 9. The semiconductor deviceevaluation apparatus according to claim 8, wherein an attenuator foreliminating a common mode of an output of the magnetic field sensor isused together with the magnetic field sensor.
 10. A semiconductor deviceevaluation apparatus comprising: a mounting section for mounting asemiconductor device for evaluation; a semiconductor device drive unitfor driving the semiconductor device mounted on the mounting section; anelectromagnetic field sensor for sensing an electromagnetic fieldemitted from the semiconductor device which is driven by thesemiconductor device drive unit; a measurement unit for measuring anoutput of the electromagnetic field sensor; an image pick-up unit fortaking a photograph of patterns of interconnects or lead frames of thesemiconductor device; a scan unit for conducting scanning with theelectromagnetic field sensor and the image pick-up unit in threecoordinate axis directions; an input unit to which information on a scanrange, a scan pitch, a scan speed of the scan unit or the like, andinformation on settings of the image pick-up unit and the measurementunit and the like are supplied as inputs; a control unit for controllingthe scan unit, the image pick-up unit, the measurement unit according toinformation which is supplied as inputs to the input unit; wherein thecontrol unit also receives information from the measurement unit and theimage pick-up unit; a record unit which prepares and stores atwo-dimensional electromagnetic distribution based on informationobtained from the measuring unit and the image pick-up unit by way ofthe control unit; an arithmetic unit which not only extract an emittedelectromagnetic field distribution higher than a threshold value whichcan arbitrarily be set based on a two-dimensional electromagnetic fielddistribution which is prepared in the record unit, but also specifies aninterconnect and a lead frame of the semiconductor device which arelarge in emission quantity by projecting the extracted electromagneticfield distribution on the image from the image pick-up unit; and anindication unit for indicating the two-dimensional electromagnetic fielddistribution prepared by the record unit, the emitted electromagneticfield distribution with a high strength having a linear shape preparedby the arithmetic unit and the image from the image pick-up unit.
 11. Amagnetic field sensor comprising: a first layer configured by a C shapedconductor pattern with a narrow gap, a straight line conductor patternhaving an almost constant and rectangular shape in section wherein eachside of the continuously sectioned C shaped conductor pattern beingstraight and the two sides of C shaped conductor nearing a gap part ofletter C being placed along the same straight line, and the straightline conductor pattern being connected to the middle point of thecontinuous side of C shaped conductor pattern, wherein all the conductorpatterns are formed in the same plane. Each of the two sides nearing thegap part of C shaped conductor is placed parallel to the straight lineat the continuous side of C shaped conductor having longer length thanthe two sides nearing the gap of C shaped conductor; a second layerconfigured by a U shaped conductor pattern being formed on a planeparallel to the plane on which the C shaped conductor pattern is formed.The U shaped conductor pattern has almost rectangular sectional shapeand straight and constant sides besides having a shape almostoverlapping the half portion of the C shaped conductor pattern, whereinthe length of each of two parallel sides of U shaped conductor havelength longer than the each of two sides of C shaped conductor nearingthe gap part of the C shaped conductor; a third layer configured by thesame conductor pattern and sectional shape as those of the first layer,the layer is provided on the plane such that the second layer isinterposed between the first and the third layer such that the resultingmulti-layer structure has symmetric structure sandwiching the secondlayer, and the multi-layer configured by superposing said first to thirdlayers though insulating layers having the same thickness and the samedielectric constant, wherein one end of the U shaped conductor patternof the second layer is connected to one end of C shaped conductorpattern near the gap of the C shaped conductor, through a via,electrically connecting the first and third layers across the gap. Thevia is provided at one end of C shaped conductor pattern near the gap ofthe C shaped conductor; ends of the straight conductor patterns of thefirst and third layers which are not connected to the C shaped conductorpatterns are electrically connected to each other through a via forconnection wherein an electrical load is connected to between the end ofthe straight conductor pattern of the second layer which is notconnected to the U shaped conductor pattern and the via; and a voltageproduced between the end of the straight conductor pattern of the secondlayer not connected to the U shaped conductor pattern and the via isused as a magnetic field sense output.
 12. The magnetic field sensoraccording to claim 11, wherein widths of the conductor patterns of thesecond layer is smaller than those of the conductor pattern of each ofthe first and third layers; and an end of the straight conductor patternof the second layer not connected to the U shaped conductor pattern isconnected to a central line of a coaxial connector, and an outerconductive line of the coaxial connector is connected to end of thestraight conductor pattern of the first and third layers not connectedto the C shaped conductor pattern.
 13. The magnetic field sensoraccording to claim 12, wherein rectangular conductor patterns with holesare formed such that the outer conductive line of the coaxial connectorpenetrate to connect the first and third layer; an end of the straightline conductor pattern not connected to the C shaped conductor patternof the first and third layers are connected to the rectangular conductorpatterns respectively formed on the first and third layer by the outerconductive line of the coaxial connector.
 14. The magnetic field sensoraccording to claim 13, wherein a base member layer having a rectangularconductor pattern constructed from a base member is provided either onthe front side or backside of the first or the third layer, or bothsides of the first or the third layer and the layers; and the each layeris connected through a via.
 15. The magnetic field sensor according toclaim 11, wherein a base member is provided either on the front side orbackside of the C shaped conductor pattern, or both sides of the Cshaped conductor pattern
 16. The magnetic field sensor according toclaim 14, wherein thicknesses of additional base members are preparedequal and the additional members are provided on both front side andbackside of the second layer sandwiched such that a symmetricalstructure is constructed.
 17. The magnetic field sensor according toclaim 11, wherein the length of one side of the C shaped conductorpattern is almost equal to that of a base member.
 18. The magnetic fieldsensor according to claim 11, wherein a base member of a given length isprovided at more than one part or across the total length of a sideclose to the via.
 19. The magnetic field sensor according to claim 11,wherein the second layer has a connect ion via of a semicircular shapeat a position where the connection via is confined within an inner spaceof the ring-like C shaped conductor pattern and an outer portion of theconnection via is located outside of the ring-like C shaped conductorpattern.
 20. A fabrication process for a magnetic field sensorcomprising the steps of: sandwiching a second layer, having a signalline constituted of a U shaped conductor pattern and a straight lineconductor pattern connected to an end of the U shaped conductor pattern,by a first and a third layer, which acts as grounds, besides having a Cshaped conductor pattern and a straight line conductor pattern connectedto a middle point of the continuous side of a ring like C shapedconductor pattern; and sequentially superposing the first, second andthird layers in the order with additional insulating layers insertedtherebetween besides connecting an end of U shaped conductor pattern ofthe second layer to an end of each of the C shaped conductor patterns ofthe first and third layers by way of a via, passing through a gapbetween the C shaped conductor patterns, wherein one part of a land fora via connection is made to exist within the inner space of thering-like C shaped conductor pattern while the other part of the land ismade to exist outside of the ring-like C shaped conductor pattern in thecase diameter of the land required for providing the via on the secondlayer having U shaped conductor pattern is not confined within width ofthe C shaped conductor pattern; and the extended part of the via outsidethe C shaped conductor pattern is removed along the edge of the C shapedconductor pattern and in the case positioning of the connection via isconducted such that the land is extended over the periphery of the outerside of the C shaped conductor pattern.
 21. A semiconductor deviceevaluation program product stored in a storage medium for evaluating anelectromagnetic field emitted from a semiconductor device, using asemiconductor device evaluation apparatus including: an electromagneticfield sensor, for measuring a two-dimensional electromagnetic fielddistribution in a plane parallel to the upper surface of thesemiconductor device; a computer to which an output of theelectromagnetic field sensor is supplied as an input; and a display fordisplaying data supplied from the computer as an output; the programcauses a semiconductor device evaluation apparatus to: extract anelectromagnetic field distribution higher than a threshold valuedetermined in advance from an electromagnetic field distribution of asemiconductor device measured by the electromagnetic field sensor;convert the electromagnetic field distribution to a distribution imagein the two-dimensional plane; collate the distribution image with aprojected image of interconnects and lead frames of the semiconductordevice which have been generated; and specify the interconnect or thelead frame which is superposed on each other as an emission source ifthe images of the electromagnetic field distribution, and theinterconnects and lead frames are superposed on one another by thecollation.
 22. The semiconductor device evaluation program productstored in the storage medium according to claim 21, wherein the programfurther causes the semiconductor device evaluation apparatus to extractthe electromagnetic field distribution by using commands to:sequentially set a plurality of threshold values; classify theelectromagnetic field emitted from the semiconductor device between themaximum and minimum strength level into a plurality of strength levelintervals of emission based on each of the plurality of threshold valuesset sequentially; wherein the program further causes the semiconductordevice evaluation apparatus to specify an emission source by using acommand to: specify the interconnect or the lead frame which correspondsto each emission strength level interval.
 23. The semiconductor deviceevaluation program product stored in the storage medium according toclaim 22, wherein the program further causes the semiconductor deviceevaluation apparatus to specify an emission source by using commands to:rearrange the lead frames in the order of emission strength levelintervals and; transmit newly ordered lead frame information as anoutput to the display.
 24. The semiconductor device evaluation programproduct stored in the storage medium according to claim 23, wherein theprogram further causes the semiconductor device evaluation apparatus toextract the electromagnetic field distribution by using commands to:narrow the emission strength level interval till no change appears inthe newer order of the lead frames after the rearranging the emissionstrength level order of each lead frames attained by specifying anemission source.
 25. The semiconductor device evaluation program productstored in a storage medium according to claim 24, wherein the programfurther causes the semiconductor device evaluation apparatus to specifyan emission source by using commands to: transmit the synthesizedinformation of the lead frames rearranged according to the emissionstrength level interval and pin assignment data made by referencing tothe pin assignment database showing functions of lead frames in acircuit defined in advance to the display as an output.
 26. A memory forstoring data for access by a computer comprising: semiconductor deviceevaluation data stored in the memory; the data includes: pin assignmentdata each of which shows a function in a circuit of a corresponding leadframe of the semiconductor device; electromagnetic field strength datawhich shows an electromagnetic field strength which has been sensed bythe electromagnetic field sensor on each pin; and sets of order dataeach set of which defines a level in the order of electromagnetic fieldstrength level for a pin corresponding to the electromagnetic fieldstrength data, wherein the pin assignment data and the electromagneticfield strength data are related with each other by a level defined inthe order according to the sets of order data.
 27. A semiconductordevice evaluation apparatus comprising: an electromagnetic fieldmeasurement means for measuring an electromagnetic field distributionemitted from a semiconductor device; an electromagnetic fielddistribution extracting means for extracting a distribution of anelectromagnetic field higher than a threshold value determined inadvance and positional information of the distribution from anelectromagnetic field distribution of a semiconductor device which ismeasured by the electromagnetic field measurement means; and a partspecifying means for specifying a part of the semiconductor device whichis high in emitted electromagnetic field among parts thereof based onthe positional information of the electromagnetic field distributionwhich is extracted by the electromagnetic field distribution extractingmeans.